Fastener having folded, split-ring helical lock washer retained thereon



Jan. 29, 1957 O J POUPITCH LOCK WASHER RETAINED THEREON Filed May 4, 1955 United States PatentI FASTENER HAVING FOLDED, SPLIT-RING HELI- CAL LOCK WASHER RETAINED THEREON Ougljesa Jules Poupitch, Itasca, Ill., assignor to Illinois Tool Works, Chicago, Ill., a` corporation of Illinois Application May 4, 1955, Serial No. 505,898

7 Claims. (Cl. ISI-37) The present invention relates to a novel preassembled fastener unit, and more particularly to a novel fastener unit including a rotary threaded fastener member such as a nut or a screw and a split-ring type lock washer.

An `object of the present invention is to provide a novel preassembled unit including a threaded fastener member and a split-ring lock washer which are interconnected so as to preclude axial separation thereof and which function so as to provide the unit with substantially improved resistance to unauthorized retrograde turning or loosening after the unit has been tightened against a workpiece.

A more specific object of the present invention is to provide a novel preassembled fastener unit of the above described type wherein the lock washer is formed in a novel manner to provide substantially improved locking action, and more particularly the lock washer is formed so that it may be initially compressed under relatively light loads to insure proper seating of the margins of the washer against the fastener member and the work, whereupon the washer provides high resistance to further compression and a substantially stronger spring action for effectively locking the fastener member against retrograde movement.

A further object of the present invention is to provide a novel unit of the above described type which is constructed so as to preclude complete attening of the lock washer in order to prevent injury thereto and in order to insure that an edge thereof will always be positioned for aggressively engaging the workpiece.

A still further object of the present invention is to provide a novel preassembled fastener unit of the above described general type wherein the fastener member and the lock washer are constructed positively to resist relative rotation therebetween after the unit has been clamped against a workpiece.

Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings wherein:

Fig. l is a fragmentary elevational view of a fastener unit embodying the principles of this invention;

Fig. 2 is a fragmentary sectional view taken along line 2*-2 in Fig. l and further showing the unit clamped against a workpiece;

Fig. 3 is a perspective view of ythe novel split-ring type lock washer incorporated in the fastener unit of the present invention;

Fig. 4 is a fragmentary elevational view showing a modified form of the present invention;

Fig. 5 is a fragmentary sectional View takenialong line 5-5 in Fig. 4 and further showing the fastener unit clamped against a workpiece;

Fig. 6 is a perspective view showing the novel lock washer utilized in the fastener unit of Figs 4 and 5; i

Fig. 7 is a perspective view showing a further slightly modified lock washer which may be used in combination with the fastener member shown in Figs. 4`an d 5; and

Fig. 8 is a fragmentary cross sectional viewof the fastener member shown in Figs. 4 and 5.

2,779,376 Patented Jan. 29, 19-57 rice Referring now more specifically to the drawings where` in like parts are designated by the same numerals through out the various figures, a fastener unit l() embodying one form of the present invention is shown in Figs. l through 3. This fastener unit includes a screw member 12 and a lock washer 14. The screw member comprises a head 16 having a radially extending clamping face 18, and an elongated shank 2t) having a plurality of helical thread convolutions 22 thereon.

The sheet material lock washer i4 is preferably formed from spring steel and includes a generally frusto-conical section 24 which is split and helically twisted in the manner shown. The smaller end of the section 24 is disposed adjacent the clamping face of the screw member and is folded inwardly as at 26 and integrally joined with an inner frusto-conical section 2S. The internal diameter of the folded portion 26 is less than the outer diameter of the thread convolutions 22, and, in addition, the lock washer is helically twisted oppositely from the helical formation of the thread convolutions whereby the thread convolutions serve to trap the washer in assembled relationship with the screw member.

It should be noted that the free peripheral edge of the outer washer section 2d is disposed substantially radially outwardly from the free edge of the inner section Z3 for engaging a workpiece 30 in the manner shown in Fig. 2. Furthermore, the diameter of the outer edge of the section 24 is substantially greater than the diameters of the head and shank so that it engages the workpiece at points spaced a relatively great distance from the axis of the screw whereby the resistance of the Washer to turning relative to the workpiece is improved.

When the unit ltl is clamped against `the workpiece, the washer is first compressed so that the helical shape thereof is flattened. The folded portion 26 and the double thickness of material provided by the inner and outer conical sections 24 and 23 offer a relatively great resistance to such flattening and therefore improves the locking characteristics of the unit. After the Ainitial compression or flattening of the helix has been accomplished, the outer peripheral edge .of the section 24 is pressed firmly against the workpiece and further tightening of the unit causes the conical sections to be axially compressed as shown in Fig. 2. The frusto-conical formation of the` sections 24 and 2S provides an even greater resistance to collapsing than the helical formation of the washer whereby the locking characteristics of the unit are further substantially improved. It has been found that by undercutting the clamping surface liti or by providing these surfaces with a frusto-conical shape in the manner shown, the clamping surface tends to restrain the washer against radial spreading and axial collapsing whereby the locking eectiveness of the unit is still further improved. It should be noted that the helical formation of the washer may be collapsed rela-tively easily as compared with the conical formation thereof so as to promote engagement of the folded portion 26 about its entire periphery with the clamping face f8 and to promote engagement of the entire peripheral outer margin of the section 24 with their workpieces in order to obtain the maximum locking action. it should also be noted that the inner section 2S of the washer will act as an abutment to prevent complete collapsing of the outer section 2e as shown in Fig. 2 so as to insure that the outer peripheral edge of the section Zfi will always aggressively engage the workpiece.

In Figs. 4, 5, 6 and 8 there is shown .a modified form of the present invention which is similar to the above described structure as indicated by the application of identical reference numerals with the suffix a added to corresponding elements. This embodiment diersin that andere.

the smaller end' of the section 24a is initially slightly flattened as` at 32, and a plurality of circumferentially spaced slots 34 are formed in the slightly iiattened portion 32, the folded .portion 26a and the inner sectionla, as shown; In addition, the screw member is provided with applurality of ribs 36 spaced'around the clamping face 13a and projectingaxially. The ribs 36 are adapted to cooperate with tooth edges defining the slots 34 in the washer to positively interlock the screw member and the washer against relative rotation.

in Fig. 7 there is shown a washer lib which is similar' to the above described washer 14a and is adapted to be used in place of the washer Ma in combination with the screw member ida. The washer Mb diners only in that it is-provided-with a plurality of tooth elements 3S spaced circumferentially on the outer margin ofthe washer section 24h for biting into a workpiece and even more securely restraining relativerotation between the' wol-iipiece and the washer. it will be appreciated that, if desired, tooth elements similar to the elements 3S may be provided on the outer margin of the washer shown in Figs. l through 3 and described above.

From the above description it is seen that the present invention has provided a novel preassembled fastener unit fully capable of satisfying the objects heretofore set forth. More specically, it is seen that the present invention has provided a novel preassembled fastener unit wherein the washer is formed to provide double compressibility so as to facilitate initial application and to improve the locking characteristics thereof, and wherein means is provided for preventing complete collapsing of the washer and other means is provided for positively resisting relative rotation between the washer and either the fastener member or the work. The rotary threaded fastener member has been disclosed herein as being a screw member, but it is understood that in certain installations, the screw member may be replaced by a nut member or the like.

While the preferred embodiments of the present invention have been shown and described herein, it is obvious that many structural details may be changed without departing from the spirit and scope of the appended claims.`

The invention is claimed as follows:

l. A preassembled rotary fastener unit comprising a threaded rotary fastener member having a generally radially extending clamping face and integral retaining means spaced axially outwardly from said clamping face and projecting generally radially, and a sheet material lock washer including a generally frusto-conical splitring section having a smaller end 'disposed adjacent said clamping face, a second frnsto-conical split-ring section disposed within said first section and having a smaller end overlying said retaining means, and a split-ring folded section integrally joining the smaller ends of said iirst and second mentioned truste-conical sections, said first mentioned section having a free peripheral edge disposed lradially and axially outwardly from a free peripheral edge of said second mentioned section.

2. A preassembled rotary fastener unit comprising a threaded rotary fastener member having a generally radially extendiny clamping face and integral retaining means `spaced axially outwardly from said clamping face and projecting generally radially, and a sheet'material lock washer including a generally frusto-conical, helically twisted split-ring section having a'smaller end disposed adjacent said clamping face, a second frusto-conical, helically twisted split-ring section disposed within said iirst mentioned section and having a smallerend over-v lying said retaining means, and asplit-ring folded section integrally joining the smaller ends of said'rst and second mentioned frusto-conical sections, said first mentioned sectionhaving a free peripheral edge-'disposed' radially 3. A- preassembledrotary fastener unit' comprisingv a threaded rotary fastener member having a generally radially extending clamping face, a plurality of 'circumferentially spaced axially projecting protuberance means on said clamping face and integral retaining means spaced axially outwardly from said clamping face and projecting generally radially, and a sheet material lock washer including a generally fiu-sto'co-nical, helically twisted split-ring section'4 having. a smaller end disposed adjacent said clampingface; means-providing tooth edges onsaid smaller end cooperable with said protuberance means for restraining relative rotat-ion-bet-weenl saidy locky washer and `said"fzistenerrmenrber;` a"secondfrustofconical, heli cally twisted-split-ringsectionV disposed withinflsaid first mentioned section and having a smaller end overlying said retaining means; anda helically twisted split-ring folded section integrally joining the smaller ends of said first and second mentioned frusto-conical sections, said irstmentionedfsection having: a free peripheral. edge disposed radially and axially outwardly from a free peripheral edgeof said second section.

4. A preassembled `fastener unit comprising threaded rotary fastener member having a generally radially extending clamping face and integral retaining means spaced axially outwardly from said clamping face and projecting generally radially, .and a sheet material lock washer including a generally truste-conical, helically twisted split-ringsection havinga smaller end disposed adjacent said clamping face, a second frusto-conical, helically twisted split-ring section disposed within said first mentioned section and having a smaller end overlying said retaining means, a helically twisted split-'ring folded sec* tion integrally joining the smaller ends of saidiirst and second mentioned frusta-conical sections, and tooth means projecting from said first mentioned section radially and axially outwardly from a. free peripheral edgev of said secondsection for engaging a workpiece.

5I A preassembled fastener unit comprising a threaded rotary fastener member having a generally radially extendingclamping' face, a plurality of circumferentially spaced vprotuberance means projecting axially from said clamping face, and integral retaining means spacedv axial! ly, outwardly from said clampingface and projecting generally radially, .and a sheet material lock washer including a generally frusto-conical, helically twisted splitring section having a smallerend disposedvadj'acent said clamping face, means'providing tooth edges on said smaller end cooperable withl saidiprotuberance means for retrainingV relative rotation between said lock washer and said fastener member, a second frusto-conic'al, helically twistedsplitring section disposed within said first section andhavinga smaller end overlying said retaining means, a helically twisted split-ring foldedV section integrally joining the smaller ends of said vfirst andsecond mentioned truste-conical sections, and tooth means pro jecting from said'rst mentioned`section radially and axially outwardly from a freeperipheral edge of said' section for engagement with` a workpiece.

6.V A preassembldrotary fastener unitN comprising a threaded" rotary fastener member having a generally radially extending and' axially iiaring clamping face, and integral retaining means spaced axially outwardly from said clampingvface and projecting generally radially,`and asheet material lock washer including a generally frusto` conical, helically twisted split-ring, section havingy a smaller end disposed adjacent said clamping face, a'second frusto-conical,vh helically` twisted split-ring section dis'- posed'within.said`iirst'mentioned section and having a smaller end overlyingsaidretaining means, anda helically twisted split-ring folded section integrally joining the smallerendsof said first and'second mentioned'frustoconical sections," said ti'ring clamping face serving, to resist radialsp'readin'g and collapsing of the lwasher when the' unit isl applied "toa workpiece.

7. AI preassembld'rotary fastener unit comprisinga threaded rotary fastener member having a generally- 5 radially extending clamping face and integral retaining means spaced axially outwardly from said clamping face and projecting generally radially, and a sheet material lock Washer including a generally frusta-conical, helically twisted split-ring section having a smaller end disposed adjacent said clamping face, a second frusto-conical, heli cally twisted split-ring section disposed within said first section and having a smaller end overlying said retaining means and a larger end substantially against said first mentioned section, and a helically twisted relatively sharply folded split-ring section integrally joining the smaller ends of said lirst and second mentioned f-rustoconical sections, said first mentioned section having a peripheral edge disposed radially and axially outwardly from the larger end of said second mentioned section.

References Cited in the le of this patent UNITED STATES PATENTS 1,504,511 Ross Aug. l2, 1924 1,631,819 Ivory June 7, 1927 1,847,314 Stoll Mar. 1, 1932 2,270,813 Olson Ian. 20, 1942 2,278,062 DeKoharovieh Mar. 31, 1942 2,372,653 Becket Apr. 3, 1945 2,424,208 Poupitch July 15, 1947 2,681,678 Hage June 22, 1954 

